This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld

SPOTLIGHT

Articles of Significant Interest Selected from This Issue by the Editors

Type III secretion systems (TTSS) allow certain bacteria to translocate virulence factors directly into host cells. Although Bordetella pertussis expresses genes encoding components of the TTSS machinery, it had been assumed that B. pertussis did not have a functional TTSS. Fennelly et al. (p. 1257-1266) demonstrate expression of TTSS substrates in clinical isolates but not in common laboratory-adapted strains of B. pertussis. A TTSS mutant induced stronger innate and adaptive immune responses and lower lung colonization in mice than did the wild type. The findings demonstrate that B. pertussis does express a functional TTSS, which confers virulence by subverting protective immune responses of the host.

Comparison of Carbon Nutrition for Pathogenic and Commensal Escherichia coli Strains in the Mouse Intestine

The Human Microbiome Project will characterize our microbiota and factors that influence microbial diversity. Once we know "who is there" we can begin asking "what are they doing there"? In this context, using Escherichia coli colonization of the mouse intestine as a model, Fabich et al. (p. 1143-1152) compared the sugars used by enterohemorrhagic E. coli (EHEC) and commensal E. coli K-12. They found that EHEC uses three sugars also used by K-12 and an additional five sugars not used by K-12. The results suggest a strategy whereby invading pathogens gain advantage by simultaneously consuming several sugars that are available because they are not consumed by the intestinal microbiota.

Group A Streptococcus Degrades Human Chemokines To Modulate the Immune Response

Circumvention of the host innate immune response is critical for bacterial pathogens to infect and cause disease. Sumby et al. (p. 978-985) show that the group A Streptococcus (GAS) protease SpyCEP (Streptococcus pyogenes cell envelope protease) cleaves granulocyte chemotactic protein-2 (GCP-2) and growth-related oncogene alpha (GRO), two potent chemokines made abundantly in human tonsils. They show that cleavage of GCP-2 and GRO abrogates the ability of these chemokines to prime human neutrophils for activation. In addition, using a mouse soft-tissue model of infection they demonstrate that SpyCEP contributes to invasive GAS infections. Thus, SpyCEP is a key GAS virulence determinant.

A Heparin-Binding Protein from Meningitic Escherichia coli

The pathogenesis of meningitis due to Escherichia coli is a complex process that requires sequential traversal of both epithelial and endothelial cell barriers. It has previously been shown that the Hek protein contributes to invasion of epithelial cells. Fagan et al. (p. 1135-1142) demonstrate that the target for Hek is heparinated proteoglycan. This interaction is facilitated by a surface-exposed stretch of 25 amino acids in the Hek protein. The authors also show that this amino acid motif is required for bacterial autoaggregation. These findings highlight yet another mechanism by which extraintestinal E. coli gains access to the interior of epithelial cells.

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld